Cable termination



Oct. 24, 1967 A. ZIMMERMAN 3,349,165

CABLE TERMINATI ON I Filed Nov.' 8, 1966 INVENTOR.

A. ZlM/ME MAN BY /%/J m 4cm United States. Patent 3,349,165 CABLETERMINATION Arie Zimmerman, Los Angeles, Calif. Anaconda Wire and CableCo., 605 3rd Ave., New York, NY. 10016) Filed Nov. 8, 1966, Ser. No.592,920 6 Claims. (Cl. 174-75) ABSTRACT OF THE DISCLOSURE In a cabletermination, the combined outer conductor and jacket are pressed into adouble-walled ferrule. The invention features a ferrule having its innertubular wall longer than its outer wall.

My invention relates to a cable termination and particularly to atermination for a coaxial cable where the outer conductor and the jacketof the cable are firmly bonded together.

A type of electric cable has recently assumed commercial importancehaving the outer jacket bonded firmly to an underlying metal conductoror shielding which is most usually comprised of aluminum. Such a cableis exemplified by the coaxial cable described in application SerialNumber 422,275 assigned to the assignees of the present invention.

It is difficult to terminate this cable by conventional means since thejacket cannot be removed from the conductor for the purpose of clampingor soldering on a connection. The problem is aggravated when theconductor is aluminum due to the well known fact that the oxide layer onthe surface of aluminum offers an obstacle to making a sound electricalconnection.

By my invention I propose to make a cable termination that is veryeasily applied by simple hand tools.

In the termination of my invention it is not necessary to separate thecable conductor or shielding from the jacket to which it is bonded.

I further propose in the termination of my invention to make apermanent, efficient electrical connection, even to aluminum.

And I further propose by my invention to make a termination that isparticularly advantageous for use in multitaps.

I have invented a termination in a cable having a tubular conductingmember, such for a preferred example as an aluminum member, and aninsulating jacket surrounding this member and bonded to it. Such a cablewill comprise a coaxial cable with an inner conductor and an annularwall of insulation between the inner conductor and the conductingmember. My termination embodies a unitary conducting ferrule comprisinginner and outer concentric tubes circumferentially joined at one endwith the inner tube substantially longer than the outer tube. The innertube is inserted directly under the conducting member and over the wallof insulation, and the outer tube is applied over the jacket. The outertube is compressed, preferably in the shape of a regular polygon,thereby locking the ferrule onto the cable and grounding the conductingmember.

A more thorough understanding of my invention may be gained from a studyof the appending drawing.

In the drawing:

FIGURE 1 shows an exploded pictorial view of my termination prior tocompressing the ferrule.

3,349,165 Patented Oct. 24, 1967 FIGURE 2 shows a pictorial view of thetermination of my invention.

Referring to the drawings, a coaxial cable indicated generally by thenumeral 10 is comprised of an inner conductor 11, and an annular wall ofinsulation 12 such, for example, as polyethylene or expandedpolyethylene surrounding the conductor 11. An outer aluminum conductor13, which is bonded to a plastic jacket 14, has been spread away .fromthe insulation 12 by means of a flaring tool. The jacket 14 is usuallyformed of polyethylene or polyvinylchloride. It will be understood thatalthough my invention has special utility where the conductor 13 isaluminum it is useful also for other conducting material such as copper.A metal ferrule 16 is comprised of an outer tube 17 and an inner tube 18joined together at one end 19 in a unitary structure, with the tube 18being sufiiciently longer than the outer tube 17 to proect substantiallybeyond the outer tube. The diameter of the tube 18 is such as to providea slide fit over the insulation 12, and the length of the flared portionof the conductor 13 is sufficient to insert the tube 18 and have a cutend 21 of the conductor-jacket combination project snugly against theend 19 of the ferrule 16 between the two tubes 17 and 18. After theferrule 16 is fitted in place on the cable 10 the tube 17 is compressedin a die which may conveniently be fitted within a hand tool of knowntype, to form the hexagonal shape shown in FIGURE 2. Because the tube 18is longer than the tube 17, a shoulder 22 remains after the tube 17 hasbeen compressed and this shoulder maintains a positive pressure betweenthe tube 17 and the conductor 13 breaking through the oxide layer on theconductor and insuring against loss of conductivity in the connection.The extra length of the tube 18 also prevents the edge of this tube fromcutting into the conductor 13 when the ferrule is compressed. In thisregard it should be noted that in coaxial cables of the type for whichmy invention is particularly adapted, the conductor 13 may be very thin,of the order of 6 mils, and easily cut, with a resulting electricaldiscontinuity, if the edge of the inner tube were under the length beingcompressed.

When the termination of my invention is used to make an electricalconnection the hexagonally shaped ferrule portion 16 is inserted under agrounding strap while the projecting conductor 11 is inserted into aterminal clamp. Because very little bulk has been added to the cable bymy termination a plurality of my terminations may be connected to amultitap of modest dimensions.

I have a new and useful termination for which I desire an award ofLetters Patent.

I claim:

1. A termination in a cable having a tubular conducting member and aninsulating jacket surrounding said member and bonded thereto,comprising:

(A) a unitary conducting ferrule comprising inner and outer concentrictubes circumferentially joined at one end,

(a) the inner of said tubes being substantially longer than the outer ofsaid tubes,

(b) said inner tube being inserted directly under said conductingmember, and

(c) said outer tube being applied over said jacket,

(d) said outer tube being compressed thereby locking said ferrule ontosaid cable and grounding said conducting member.

2. The termination of claim 1 wherein said outer tube 6. The terminationof claim 4 wherein said conducting is compressed in the shape of aregular polygon. member is aluminum.

3. The termination of claim 1 wherein said conducting V a member isaluminum. b1 References Cited 4. The termination of claim 1 wherein saidca e is a 5 coaxial cable having an inner conductor and an annularUNITED STATES PATENTS wall of insulation between said inner conductorand said 2 793 113 7 1957 11 et aL 17 75 conducting member and saidinner tube is inserted over 2,929,862 3/1960 Anne et aL said wall. a

5. The termination of claim 4 wherein said outer tube DARRELL L7 CLAYPrim-my Examiner is compressed in the shape of a regular polygon.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,349,165 October 24, 1967 Arie Zimmerman It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

p In the heading to the printed specification, lines 3 to 5, for 0Anaconda Wire and Cable Co., 605 3rd Ave. New York,

N. 'Y. l0016)"read assignor to Anaconda Wire and Cable Company, acorporation of Delaware column 2, line 49, after "have" insert inventedSigned and sealed this 17th day of December 1968.

(SEAL) attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER lttesting Officer Commissionerof Patents

1. A TERMINATION IN A CABLE HAVING A TUBULAR CONDUCTING MEMBER AND ANINSULATING JACKET SURROUNDING SAID MEMBER AND BONDED THERETO,COMPRISING: (A) A UNITARY CONDUCTING FERRULE COMPRISING INNER AND OUTERCONCENTRIC TUBES CIRCUMFERENTIALLY JOINED AT ONE END, (A) THE INNER OFSAID TUBES BEING SUBSTANTIALLY LONGER THAN THE OUTER OF SAID TUBES, (B)SAID INNER TUBE BEING INSERTED DIRECTLY UNDER SAID CONDUCTING MEMBER,AND (C) SAID OUTER TUBE BEING APPLIED OVER SAID JACKET, (D) SAID OUTERTUBE BEING COMPRESSED THEREBY LOCKING SAID FERRULE ONTO SAID CABLE ANDGROUNDING SAID CONDUCTING MEMBER.